Ever since motor driven vehicles have replaced draft animals for tilling the soil, a need has existed for a vehicle at least a portion of which can move laterally, and the whole vehicle of which can turn about a point falling within the confines of the vehicle. When cultivating row crops for example, any implement must come to the end of the row and then turn and go back the adjacent row. All tractors with which we are familiar, require a considerable radius which exceeds the length of the tractor with the result that it has been necessary to cultivate and plant rows at the ends of the field which run perpendicular to the main rows running lengthwise of the field. It is necessary, therefore, for the tractor to drive over some of the end perpendicular rows when cultivating lengthwise of the field, and a certain amount of the crop is lost or damaged by the wheels of the tractor used in cultivating.
A similar situation exists in vehicles used to carry or draw lawn mowers over the terrain, particularly where the mower is supported from or drawn behind the rear of the vehicle. Rotary lawn mowers have become extensively used, and in many instances the rotary mowers have been mounted directly below the frame of the tractor which supports the rotary mower. All commercial machines with which we are aware require a considerable turning radius in order for the vehicle to turn around and make another pass over the terrain with the result that there are areas at the ends of the plot being mowed which are not cut when the vehicle turns around, and which must be cut by a passage of the vehicle transversely across the main length of the plot. In such instances, the wheels of the vehicle flatten some of the grass before it is mowed, with the result that a short time after mowing the grass which has been flattened by the wheels of the vehicle become erect again to leave uncut wheel marks.
Still further difficulties exist with existing mowers, in that they dig into the terrain when the vehicle traverses a high spot or knoll. This is particularly true with vehicles having the usual front and rear pairs of wheels; and in those instances where the frames are rigid, one or more wheels may leave the ground to leave areas of grass which are high and other areas which have been removed to the bare ground.
Still other problems exist in farm vehicles which perform work relative to objects supported or raised on the ground over which the vehicle passes; so that there is no question that a need for a vehicle that can turn about a point within the confines of the vehicle has existed for a long time. It is equally clear that no such device has been produced heretofore which is sufficiently workable as to warrant commercial production.
An object of the invention therefore is the provision of a new and improved ground vehicle that is self-propelled and which can turn about a point within the confines of the vehicle.
Another object of the present invention is the provision of a new and improved self-propelled mower which can move up to an object and at least a portion of which can move laterally relative thereto to thereby trim around objects.
A further object of the invention is the provision of a new and improved self-propelled short turn land vehicle the ends of which can be made to move laterally.
Further objects and advantages of the invention will come become apparent to those skilled in the art to which the invention relates from the following description of several preferred embodiments which are described with reference to the accompanying drawings.